High-resolution structural analysis of eukaryotic ribosomal RNAs by scanning transmission electron microscopy

1984 ◽  
Vol 42 ◽  
pp. 688-689
Author(s):  
G.T. Oostergetel ◽  
J.F. Hainfeld ◽  
J.S. Wall ◽  
M. Boublik
Keyword(s):  
Ribosomal Rna ◽  
Ribosomal Proteins ◽  
Scanning Transmission Electron Microscopy ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Evolutionary Level ◽  
And Function ◽  
Similar Domain ◽  
Cellular Organelles

The structure and function of ribosomes, small cellular organelles involved in protein synthesis, are determined by both their macromolecular components - proteins and RNAs. The protein/RNA ratio depends on the evolutionary level of the organism. In eukaryotic ribosomes the protein/RNA ratio is ~ 1:1 (w/w). While the number and composition of ribosomal proteins varies from species to species, the number and composition of RNAs is highly conserved.We have chosen the 18S and 28S ribosomal RNA isolated from baby hamster kidney cells to study the structural role of eukaryotic RNAs on the ribosome. Similarity in the extent of secondary structure suggests that the eukaryotic RNAs have similar “domain” structure as their prokaryotic counterparts. This structure consists of segments of double stranded stems, single strands and loops. However, folding of these segments into a conformation contributing to the 3-D structure of the ribosome remains to be established.

Core–shell structures with metallic silver as nucleation agent of low expansion phases in BaO/SrO/ZnO/SiO2 glasses

CrystEngComm ◽  
2019 ◽  
Vol 21 (29) ◽  
pp. 4373-4386 ◽  
Author(s):  
Christian Thieme ◽  
Michael Kracker ◽  
Katrin Thieme ◽  
Christian Patzig ◽  
Thomas Höche ◽  
...  
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
Nucleating Agent ◽  
Shell Structures ◽  
Metallic Silver ◽  
X Ray Diffraction ◽  
Nucleation Agent ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

The role of silver as a nucleating agent in BaO/SrO/ZnO/SiO2 glasses is studied with a range of microstructure-characterization techniques, such as scanning transmission electron microscopy, ultraviolet-visible spectroscopy, and X-ray diffraction.

NANOSTRUCTURAL ANALYSIS OF A GaN-BASED VIOLET LASER DIODE

2008 ◽  
Vol 15 (01n02) ◽  
pp. 189-193
Author(s):  
J. R. YANG ◽  
H. L. TSAI ◽  
T. Y. WANG ◽  
H. W. YEN ◽  
C. Y. CHEN ◽  
...  
Keyword(s):  
Laser Diode ◽  
Scanning Transmission Electron Microscopy ◽  
Dark Field ◽  
Threading Dislocation ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Annular Dark Field ◽  
Strained Layer Superlattice ◽  
P Type

The nanostructure of p-type AlGaN / GaN strained-layer superlattice (SLS) cladding in a GaN -based violet laser diode (LD) has been investigated by high-angle annular dark-field (HAADF) scanning-transmission electron microscopy (STEM). The pairs of the AlGaN and GaN layers in SLS cladding are observed, where the AlGaN and GaN layers appear as dark and bright bands. It is also found that the threading dislocations disappeared within the SLS; this evidence manifests the role of SLS in suppressing threading dislocation propagation.

High-Voltage Scanning Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 6-7
Author(s):  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Wave Optics ◽  
Contrast Effects ◽  
Transmission Electron ◽  
Mode Of Operation ◽  
Scanning Transmission ◽  
Types Of Information ◽  
Voltage Scanning

The comparison of scanning transmission electron microscopy (STEM) with conventional transmission electron microscopy (CTEM) can best be made by means of the Reciprocity Theorem of wave optics. In Fig. 1 the intensity measured at a point A’ in the CTEM image due to emission from a point B’ in the electron source is equated to the intensity at a point of the detector, B, due to emission from a point A In the source In the STEM. On this basis it can be demonstrated that contrast effects In the two types of instrument will be similar. The reciprocity relationship can be carried further to include the Instrument design and experimental procedures required to obtain particular types of information. For any. mode of operation providing particular information with one type of microscope, the analagous type of operation giving the same information can be postulated for the other type of microscope. Then the choice between the two types of instrument depends on the practical convenience for obtaining the required Information.

Imaging and diffraction modes in Scanning Transmission Electron Microscopy

1986 ◽  
Vol 44 ◽  
pp. 684-687
Author(s):  
J. M. Cowley ◽  
R. Glaisher ◽  
J. A. Lin ◽  
H.-J. Ou
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
High Efficiency ◽  
Fiber Optic ◽  
Image Intensifier ◽  
Detector System ◽  
Detector Plane ◽  
Secondary Electrons ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Special Detector

Some of the most important applications of STEM depend on the variety of imaging and diffraction made possible by the versatility of the detector system and the serial nature, of the image acquisition. A special detector system, previously described, has been added to our STEM instrument to allow us to take full advantage of this versatility. In this, the diffraction pattern in the detector plane may be formed on either of two phosphor screens, one with P47 (very fast) phosphor and the other with P20 (high efficiency) phosphor. The light from the phosphor is conveyed through a fiber-optic rod to an image intensifier and TV system and may be photographed, recorded on videotape, or stored digitally on a frame store. The P47 screen has a hole through it to allow electrons to enter a Gatan EELS spectrometer. Recently a modified SEM detector has been added so that high resolution (10Å) imaging with secondary electrons may be used in conjunction with other modes.

Scanning Transmission Electron Microscopy of Polyethylene Crystals

1980 ◽  
Vol 38 ◽  
pp. 242-245
Author(s):  
F. Khoury ◽  
L. H. Bolz
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Crystallization Temperature ◽  
Scanning Transmission Electron Microscopy ◽  
Growth Habit ◽  
Lateral Growth ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Growth Habits

The lateral growth habits and non-planar conformations of polyethylene crystals grown from dilute solutions (<0.1% wt./vol.) are known to vary depending on the crystallization temperature.1-3 With the notable exception of a study by Keith2, most previous studies have been limited to crystals grown at <95°C. The trend in the change of the lateral growth habit of the crystals with increasing crystallization temperature (other factors remaining equal, i.e. polymer mol. wt. and concentration, solvent) is illustrated in Fig.l. The lateral growth faces in the lozenge shaped type of crystal (Fig.la) which is formed at lower temperatures are {110}. Crystals formed at higher temperatures exhibit 'truncated' profiles (Figs. lb,c) and are bound laterally by (110) and (200} growth faces. In addition, the shape of the latter crystals is all the more truncated (Fig.lc), and hence all the more elongated parallel to the b-axis, the higher the crystallization temperature.

Sign in / Sign up

Export Citation Format

Share Document